Authentication failed with LDAP server.

I installed the latest RQM server on my server. The OS is SLES 11 SP1, the database is DB2, and I use the IBM internal LDAP, and I used the default Tomcat as the web server. Licenses are imported successfully to support 250 people. Users in LDAP had been retrieved and listed in the RQM User Management, and I assigned the license for each user. But when user try to login RQM with the intranet password, they got the error "invalid user or password". Is there any one who can help me on this?